Contents

Results and comparison with previous survey

Survey sample

One hundred and four growers participated in this survey. The
sample consisted of 50 participants from the original 2014/15
survey and 54 new recruits drawn from a sample of Scottish
WOSR growers
(13). These growers collectively sowed 5,553 hectares (ha) of
WOSR on 131 farms.
This sample represents18 per cent of the 2016 Scottish crop area
(6). The areas sampled in each region reflect the geographic
distribution of Scottish oilseed rape cultivation, accounting for
between 13 and 22 per cent of the crop grown in the main
WOSR producing
regions (
Table
1).

The total area of
WOSR sown in
Scotland decreased by 14 per cent between 2014 and 2015 (35,198 and
30,141 ha, respectively)
(6). The 2015/16 crop area is 9 per cent lower than the ten year
average of 33,263 ha (2007 to 2016) reported in the Scottish
agricultural census
(6). There were also reductions in areas of winter cereals sown
in 2015 and these declines in winter crops were in part attributed
to the late harvest in 2015, followed by a period of very wet
weather, which made planting autumn-sown crops problematical
(14). These difficulties were encountered by several farmers who
were contacted in relation to the survey. Four potential
participants, who had collectively intended to sow over 800 ha of
WOSR in autumn 2015,
stated that they were unable to do so due to the late harvest or
wet weather at sowing.

The number of participants, and crop area, surveyed were similar
to the previous survey in which 96 growers, collectively growing
5,465 ha, were surveyed, representing 14 per cent of the 2015
WOSR crop.

Drilling date and seed rate

All
WOSR encountered in
this survey was sown between August and September 2015. The
majority of crops were sown in August (83 per cent of growers and
84 per cent of the crop area) with most of the crop drilled in the
last two weeks of the month (81 per cent of growers and crop area)
(
Table
2).

As discussed in the previous section it has been reported that
the late 2015 harvest delayed, and in some cases prevented, sowing
of winter crops in Scotland. This delay in sowing was reflected in
our survey data for the two consecutive seasons (Figure 1).

The median seed rate was 2.5 kg/ha (range 1.4 to 5.0 kg/ha).
Hybrid
WOSR varieties were
drilled at lower rates than conventional varieties. The median seed
rate recorded in the previous survey was 3 kg/ha (range 1.2 to 6
kg/ha). This reduction in seed rate may have been influenced by
fewer of the growers in this survey increasing their seed rate as
mitigation for
CSFB damage. In
the previous survey 11 per cent of growers adapted seed spacing and
rate in autumn 2014, compared to four per cent in autumn 2015
(refer to following operational changes section).

Figure 1
WOSR sowing period
in 2014/15 and 2015/16 surveys

Operational changes in crop cultivation in response to
restrictions

Growers were asked if they had made any changes to their crop
cultivation practices to attempt to mitigate for the absence of
insecticidal seed treatments.

A total of 16 growers, 15 per cent of the sample, reported they
had made operational changes (
Table
3). These cultivation techniques were collectively applied to
847 ha, 15 per cent, of the crop surveyed. In all cases, the stated
aim of this adaptation to practice was to reduce the impact of
potential
CSFB
damage.

Six per cent of the growers surveyed, collectively growing 350
ha of crop (six per cent of the sample) adopted different soil
cultivation techniques, such as minimum tillage, strip tillage and
direct drilling. This change in cultivation was designed to allow
the earliest possible establishment of the crop, with the aim of
avoiding
CSFB migration
coinciding with crop emergence, when seedlings are most vulnerable
to damage.

A further four per cent of farmers, growing 203 ha, adjusted
drilling dates with a similar strategy of production of a
well-established crop that could out-compete
CSFB damage.
Increasing seed rate, or amending row spacing, to mitigate for
potential crop loss was implemented by four per cent of the
surveyed growers on 221 ha of land. Two participants used
fertilisers, in the form of a seed dressing and precision
fertiliser delivery at drilling on 56 and 18 ha respectively. The
aim of the fertiliser use was to encourage quicker establishment
and greater crop vigour, to compensate for insect grazing.

These 16 growers were asked if they thought that the operational
changes had helped with crop establishment and performance. The
majority of growers (seven, collectively growing 297 ha) stated
that they were unaware if their actions had made a difference to
crop performance. These growers used a range of operational changes
including using fertiliser at drilling and altering seed rate,
spacing and cultivation methods. Five growers (collectively growing
370 ha) stated that the actions had improved crop performance.
These growers amended drilling dates, soil cultivations and seed
rate. Two growers (88 ha) stated that they had seen no improvement
in the crop in response to amending soil cultivation techniques and
using a fertilising seed treatment. The remaining two growers did
not provide a response to this question.

In the previous survey, a greater proportion of the farmers
surveyed made operational changes (Figure 2). Twenty five growers
(26 per cent of the sample), collectively growing 2,032 ha and
representing 37 per cent of the crop surveyed, made one or more
cultural changes to their 2014 sown crop.

It should be noted that although the decrease in the proportion
of growers adopting operational changes was sizable it was not
statistically different between years (p=0.052).

The decision to make operational changes in the second year of
the restrictions may have been influenced by the growers' prior
experiences. In the first season, the impact of the lack of an
insecticidal seed treatment was untested, and growers had no
practical experience of whether changes to cultivation techniques
were required. In contrast, in the second year of the restrictions
their approach was informed by their experience in the preceding
year. The 2014/15 survey indicated that, in Scotland, there were
comparatively low levels of autumn crop loss to
CSFB. The
damage incurred may have been less than had been anticipated by
Scottish growers and by the agricultural industry and press. With
experience of a seed treatment free growing season, in which high
levels of damage were infrequently encountered, Scottish growers
may have considered that fewer interventions were necessary in
autumn 2015. In addition, as noted earlier, sowing conditions in
autumn 2015 were difficult, this additional pressure may also have
influenced the decreased occurrence of adaptation of
WOSR
cultivations.

Grower perception of insect pest pressure

Growers were asked to rate their perception of aphid and flea
beetle populations during crop emergence and establishment as low,
moderate or high. As comparative ranking is subjective, growers
were asked to report what methods they used to assess pest
populations (
Table
4). It is important to note that, as in the previous survey,
most respondents were growers, and their responses may not capture
all actions performed by agronomists on their behalf.

Most growers (71 per cent) used more than one information source
when assessing pest numbers. The majority (86 per cent) were
advised by agronomists about pest presence in their crops. In
addition, 60 per cent of growers reported that they conducted their
own crop walking and inspection. Other sources of information used
directly by growers included checking thresholds (28 per cent) and
using traps (one grower). In addition, 35 per cent stated that they
gained information about pest levels from technical bulletins
produced by advisory bodies and also from the farming press. Many
growers consulted more than one source of this type of general pest
warning information. Twenty four and 21 per cent of growers used
information from Scotland's Rural College (
SRUC) and the
Agriculture and Horticulture Development Board (
AHDB),
respectively and 10 per cent gained information from the farming
media.

The adoption of a range of pest monitoring methods, and the
reliance on use of agronomists and crop walking to inform growers
about pest pressure reported here, is very similar to that
encountered in the previous season (Figure 3). In 2014/15, 83 and
58 per cent of growers consulted agronomists and conducted crop
walking, respectively. However, far fewer growers reported using
thresholds (9 per cent) or consulting technical bulletins (7 per
cent). The increased use of additional methods of pest monitoring
at crop establishment encountered in the second year of the
restrictions may, as discussed previously, indicate an increase in
farmer experience and awareness of the importance of monitoring
crops to determine the necessity and timing of sprays in the
absence of a systemic seed treatment.

Figure 3 Pest assessment methods in 2014/15 and 2015/16
surveys

In relation to aphid pest pressure during crop establishment,
the majority of growers reported that populations were either low
(73 per cent) or that aphids were not seen on the crop (13 per
cent) (
Table
5). A further six per cent reported aphid numbers to be
moderate (low/moderate or moderate) and one per cent to be high.
The remaining seven per cent did not monitor aphid populations.

Reported autumn aphid levels in this survey year were lower than
in the previous year, in which 70 per cent of growers ranked aphids
as low or not seen, 21 per cent as low/moderate or moderate and
five per cent as moderate to high or high (Figure 4). The
proportion of growers reporting aphid numbers as moderate or high
in this survey was significantly lower than in the previous survey
(p<0.001). No information about the species of aphid present was
available in either survey year.

In relation to flea beetle presence, the majority of growers (82
per cent) also ranked populations as low or not seen (62 and 20 per
cent respectively) (
Table
5). A further 13 per cent ranked levels as moderate
(low/moderate or moderate) and two per cent as high (moderate/high
or high). The remaining three per cent did not monitor flea beetle
populations.

As with the aphid data, flea beetle populations were reported to
be lower in autumn 2015 than autumn 2014 (Figure 5). In 2014, the
majority of growers (62 per cent) reported flea beetle populations
to be low or not seen (45 and 17 per cent respectively). A further
25 per cent ranked levels as moderate (low/moderate or moderate)
and 10 per cent as high (moderate/high or high). The proportion of
growers reporting flea beetle numbers as moderate or high in this
survey was significantly lower than in the previous survey
(p<0.001).

Figure 4 Aphid pest pressure in 2014/15 and 2015/16
surveys

Figure 5 Flea beetle pest pressure in 2014/15 and 2015/16
surveys

Of the 21 growers who reported flea beetles on their crops, the
majority (62 per cent) identified them as
CSFB. Five per
cent stated that they were a combination of
CSFB and
Phyllotreta spp. flea beetles and five per cent as
Phyllotreta spp. only. The remaining 29 per cent did not
know which species of flea beetle were present (
Table
6).

This pattern is similar to that reported in the previous season,
in which
CSFB was also
the species most commonly reported by growers who encountered flea
beetles on their crops (51 per cent). A larger number of growers
could not identify the species present in autumn 2014 (42 per cent)
than in autumn 2015 (Figure 6). This may indicate increased grower
knowledge of the pest species present, which could be associated
with the increased use of thresholds and technical bulletins by
growers in this survey. It may also be influenced by increased
grower experience in pest identification in this second year of
neonicotinoid restrictions.

Figure 6 Species of flea beetle in 2014/15 and 2015/16
surveys

Autumn foliar insecticide use

Growers were asked to provide details of all insecticidal sprays
applied during autumn 2015. In total, 56 sprays were applied by the
104 growers surveyed; an average of 0.54 sprays per grower.

More than half of the growers surveyed (56 per cent) did not use
any insecticides in autumn 2015 (
Table
7). The majority of growers who did spray made a single
application (36 per cent of the sample). This includes 31 per cent
of growers applying a spray to their whole crop area and five per
cent of growers who sprayed part of their crop area and left some
fields untreated. Eight per cent of growers sprayed their crops
with insecticides twice and one grower applied three sprays.

In relation to crop area, 3,090 ha of the crop was untreated,
this represented 56 per cent of the survey area, and 2,463 ha
received at least one spray. Of the treated crop area, 1,844 ha was
treated once, 601 ha was treated twice and 18 ha received three
sprays (33, 11 and <1 per cent of the sampled area
respectively). The total treated area, including the repeat
applications was 3,100 ha.

In the previous survey, growers had been asked about their
pesticide use in both autumn 2013 and 2014; representing the year
preceding, and the first year after, the introduction of the
neonicotinoid restrictions (Figure 7). Fewer growers applied
insecticides in this survey than in the previous year (44 and 61
percent respectively) and 24 per cent fewer sprays per grower were
encountered (0.54 and 0.71 respectively). This reduction in the
number of sprays per grower in 2015 was statistically significant
(p<0.01).

Both the number of sprays per grower and the percentage of
growers applying pesticides in autumn 2015 were similar to those
reported in 2013 (0.48 and 47 per cent respectively), the year
before the neonicotinoid restrictions were introduced. However, no
pest population information is available for 2013; therefore it is
not possible to directly compare pest control inputs.

Figure 7 Number of autumn insecticide sprays applied by
growers in 2013, 2014 and 2015

There were also reductions in the proportion of the crop area
treated between autumn 2014 and 2015 (Figure 8). In 2014, 65 per
cent of the crop received an autumn insecticide spray, compared to
44 per cent in 2015. This information is not available for
2013.

Figure 8 Autumn insecticide sprays by crop area in
2014/15 and 2015/16 surveys

Insecticide application decision making
process

Growers were asked what information they used when making the
decision whether or not to apply a foliar insecticide to their crop
(
Table
8). A range of responses were provided, with most farmers
giving more than one reason. As this data was supplied by survey
respondents, who were primarily growers, it may not capture all
actions performed by agronomists on their behalf.

Most growers who applied an insecticide relied on an
agronomist's advice when making the decision to spray (89 per
cent). They were also informed by crop walking, use of thresholds
and by reacting to information in technical bulletins (41, 20 and 4
per cent of those who sprayed, respectively). In addition to these
reasons, nine growers (20 per cent of those who sprayed) stated
that sprays were precautionary. Those growers that did not use an
insecticide based this decision on agronomist advice (74 per cent),
crop walking (40 per cent) and use of thresholds (16 per cent).

The reasons given for spraying in this survey were similar to
those collected in autumn 2014 (Figure 9), with agronomist advice
and crop walking being the most commonly encountered followed by
use of thresholds and application of precautionary sprays.

Figure 9 Reasons for insecticide use in 2014/15 and
2015/16 surveys

Targets of pesticide use

The pests targeted by the insecticide sprays applied by growers
are presented in
Table
9. Sprays were applied to combat aphids, flea beetles and rape
winter stem weevil. However, the main focus of insecticide
applications was flea beetle control, which accounted for 65 per
cent of total sprays, and 71 per cent of the total treated area.
Aphids were a target in 9 per cent of sprays (10 per cent of
treated area). Rape winter stem weevil, which is not an approved
target of neonicotinoid seed treatments, was the focus for 25 per
cent of applications (19 per cent of treated area).

The targets encountered in autumn 2015 are very similar to those
reported in the previous survey. In autumn 2014, flea beetles,
aphids and rape winter stem weevil were the focus of 67, 4 and 22
per cent of sprays respectively and 73, 3 and 15 per cent of the
total treated area.

Insecticide active substances applied

The insecticides encountered in this survey were almost
exclusively pyrethroid compounds (
Table 10). The only exception was a single
spray of the active substance pymetrozine, a pyridine insecticide.
Four pyrethroid active substances were recorded; alpha
cypermethrin, cypermethrin, lambda cyhalothrin, and zeta
cypermethrin. Lambda cyhalothrin and zeta cypermethrin were the
most frequently used compounds, together accounting for 84 per cent
of sprays applied by growers and 80 per cent of the total area
treated.

Pyrethroid insecticides were also the most commonly used
compounds in the 2014/15 survey, accounting for all but one spray
of acetamiprid (Figure 10). A greater range of pyrethroid active
ingredients were encountered in autumn 2014, six in total, with the
most commonly used being lambda cyhalothrin, zeta cypermethrin and
cypermethrin, collectively accounting for 79 per cent of sprays
applied by growers and 84 per cent of the total area treated.

Growers were asked whether they experienced problems controlling
autumn insect pests (
Table 11). Despite concerns about the
pyrethroid resistance status of both peach potato aphid and
CSFB, the
majority of the 46 growers who applied a spray did not report any
problems with the efficacy of their pest control measures (87 per
cent).

Of the six growers that did encounter problems controlling pests
with pyrethroid insecticidal sprays, the majority (three growers)
stated that high levels of
CSFB made
foliar control difficult. These growers did not consider this a
pyrethroid resistance issue, but that large populations resulted in
a continued problem with re-infestation which, in two cases,
necessitated a second spray. One grower did state that they could
not achieve sufficient efficacy with alpha-cypermethrin against
CSFB,
necessitating a second spray to control populations. In addition,
two growers reported that weather conditions hampered spray
application at the time it was needed.

Of the 58 growers that did not apply insecticides, six stated
that they may have considered spraying but weather conditions
precluded their use at the time at which they were needed.

Very similar responses were received from growers in the
previous survey, in which 84 per cent of growers reported
encountering no problems with spray efficacy. There was no
statistical difference in response between the survey seasons
(p>0.05).

Grower perception of autumn pest damage and crop
loss

Growers were asked to rate autumn insect damage to their crops (
Table 12). They were also asked to indicate
which species they thought were responsible for the damage
incurred.

Insect damage, during the 2015 crop emergence and establishment
period was rated as low by the majority of growers (67 per cent of
growers and sample area). An additional 15 per cent of growers did
not report any insect damage to their crops. Therefore, 82 per cent
of growers, collectively growing 83 of the sampled crops, reported
no or low insect damage in 2015. Fifteen percent of growers
reported damage to be moderate (low/moderate or moderate) and one
per cent reported high damage levels.

In autumn 2014, the proportion of growers reporting damage as
moderate (28 per cent) or high (six per cent) was significantly
greater than in this survey (p=0.001) (Figure 11). The reduced
insect damage incurred in autumn 2015 reflects the reduced pest
pressure encountered in this survey.

Figure 11 Autumn insect damage in 2014/15 and 2015/16
surveys

Growers were asked to identify the insect pests causing autumn
damage to their crops (
Table 13). As would be expected,
CSFB was the
most commonly cited species (61 per cent of growers). Aphids are a
vector of virus and symptoms are not apparent until later in the
growing season (information about viral monitoring and incidence is
presented in the post-harvest section of this report). This pattern
is similar to the previous survey, in which the majority of autumn
insect damage incurred was attributed to
CSFB.

In addition to asking growers to rank damage, they were also
asked whether they thought that the lack of seed treatment had
resulted in greater autumn insect damage to their crops in 2015
than in the period before the restrictions were in place (
Table 14). Thirty eight per cent of growers
responded yes, 54 per cent responded no and 8 per cent were not
sure. These growers collectively cultivated 48, 47 and five per
cent of sample area respectively. In 2014/15 the responses were 46
per cent yes, 49 per cent no and five per cent don't know.

Details of non-insect pest related damage to crops in autumn was
also recorded (
Table 15). Almost all growers (94 per cent)
reported experiencing other pest damage. The most frequent pests
encountered were slugs, which were reported by 83 per cent of
growers, followed by pigeons reported by 29 per cent. Rabbits,
geese and deer were also reported to have damaged
WOSR crops by a
small number of growers.

For some growers, failure of the crop during emergence and
establishment resulted in re-drilling of a proportion of the sample
area (
Table 16). Of the 104 growers and 5,553 ha
surveyed, seven growers collectively re-drilled 98 ha of failed
crop (1.8 per cent of sample area). Of that area, 39 ha (0.7 per
cent of the sample), grown by four farmers, were re-drilled due to
damage from non-insect pests (slugs and geese). The remaining 59 ha
(1.1 per cent of sample), grown by three farmers, was lost to poor
weather at drilling and establishment. No crop loss was attributed
to insect damage in 2015/16.

The overall level of crop loss encountered in this survey was
very similar to the previous year in which 2.4 per cent of the
sample was lost. There was no statistical difference in the number
of growers who redrilled crops between the two years (p>0.05).
In 2014/15, 1.1 per cent of the crop area was re-drilled due to
CSFB damage and
the remaining 1.3 percent was lost due to weather at drilling, poor
seed vigour and damage from slugs, rabbits and pigeons.

Post-harvest data collection

All 104 growers were contacted post-harvest to collect data
about
TuYV incidence,
yield and their attitude towards growing
WOSR in the future.
However, not all of the original participants responded at the
second data collection point. Post-harvest data were collected from
98 growers, collectively growing 5,170ha of
WOSR (17 per cent of
the Scottish crop area).

Incidence of
TuYV

Of the 98 growers who provided information, the majority (85 per
cent) reported that their crops were visually checked for symptoms
of
TuYV and five per
cent reported that viral symptoms were present. This is very
similar to the pattern reported in the previous season when 79 per
cent of growers checked their crops and four per cent reported the
presence of symptoms.

In both years only one grower had crop samples tested for
TuYV. In this survey
the test was negative, in contrast to the previous survey where
viral presence was confirmed. As discussed in the previous report,
TuYV may be
asymptomatic and can only be definitively diagnosed by serological
testing. Therefore these data may underestimate viral presence.
There were no significant differences in the proportion of growers
checking for
TuYV or for the
observation of symptoms between the two surveys (p>0.05).

Crop yield

The average 2016
WOSR yield reported
by the growers in this survey was 3.46 tonnes per hectare (t/ha),
with a regional range of 3 to 3.85 t/ha (
Table 17). This is similar to the 2016
Scottish average yield of 3.31 t/ha reported by the Scottish
Government
(15).

The majority of growers reported decreased yields in 2016 (84
per cent of growers, 87 percent of crop area). The remaining
growers reported that yields were unchanged from the previous
season (nine and eight per cent of growers and crop area
respectively) or had increased (seven and five per cent of growers
and area). Average yield declined in all geographic regions
surveyed.

In the previous survey, yields of 4.21 and 4.28 t/ha were
reported for 2014 and 2015 respectively (Figure 12). The 2016
survey yield is 19 per cent lower than that reported in 2015 and
this decrease is statistically significant (p<0.001). There was
also evidence of a significant interaction between yield and region
(p=0.002), suggesting that the magnitude of yield change was not
constant amongst regions.

Figure 12 Average
WOSR yield of
survey area in 2014, 2015 and 2016

Scottish census data
(15) also show a 20 per cent decrease in total Scottish oilseed
rape yields in 2016 from the 20-year high yield of 4.15 t/ha in
2015 (Figure 13).

Whilst fluctuations of Scottish yield have been marked in recent
years, it was reported that the large decrease in yield in 2016 was
influenced by strong winds prior to harvest
(15). This was confirmed in our survey, in which the majority of
growers who experienced a decrease in yield attributed this to the
weather during the growing season (66 per cent stating weather
alone and a further 14 per cent stating weather among other
factors) (
Table 18). A range of contributing weather
conditions were reported to have influenced yield decline; high
winds prior to harvest causing seed shed (35 per cent of growers),
a lack of sun in late spring/summer causing retardation of crop
flowering, growth and impaired grain fill (28 per cent), wet
conditions in autumn/winter hampering establishment (23 per cent)
and crop growth retarded by the cold spring (six per cent). As well
as poor weather conditions, yield was also reported to have been
affected by other factors such as disease (clubroot), pigeon and
slug damage as well as by weed growth, poor soil and late drilling
in autumn 2015. Two growers, representing five per cent of those
experiencing yield losses, reported that the
CSFB damage had
contributed to the decline. Both of these growers, who were located
in the south of Scotland, also stated that lack of sun had also
influenced yields.

Overall, the growers surveyed reported that a range of factors
had contributed to the decline in yield, but that weather
conditions, and in particular high winds pre-harvest, were the
primary driver responsible for yield declines in comparison to the
previous season.

Grower attitudes to future
WOSR
cultivation

Following harvest, growers were asked whether, based on their
current experience, they would grow oilseed rape in future. The
majority stated that they would continue to grow
WOSR (75 per cent),
16 per cent stated that they would be less likely in future, six
per cent more likely and three per cent didn't know. There was no
significant difference in reported intentions of future
WOSR cultivation
between survey years (p>0.05, Figure 14).

Growers were given the opportunity to comment on their response.
Of the 15 growers who stated that they were less likely to grow
WOSR in future,
eight provided comments. Five stated that this decision was
unrelated to the availability of seed treatments; but was
influenced by general economic return, cultivation of alternative
break crops and problems with slugs.

The other three growers were influenced by the neonicotinoid
restrictions. These growers reported that the additional inputs and
risk required to grow
WOSR in the absence
of insecticidal seed treatments made the crop less attractive.

In relation to those growers who specified that they would not
change their
WOSR cultivation,
the majority stated that they had not encountered problems
associated with the lack of an insecticidal seed treatment.
However, some stated that they would reassess if this changed in
future. Of the 6 growers who intended to sow more in 2017, all
stated that this was due to not having encountered problems during
the neonicotinoid restrictions, with one also citing increasing
market price.

As with the previous survey, the common theme from growers was
that the main drivers in choosing whether
WOSR was grown in
future were market price, input costs and economic return.